Resist pattern forming method, semiconductor apparatus using said method, and exposure apparatus thereof

ABSTRACT

In immersion exposure, a resist pattern forming method suppressing resist pattern defects comprises mounting a substrate formed a resist film thereon and a reticle formed a pattern thereon onto an exposure apparatus, supplying a first chemical solution onto the resist film to selectively form a first liquid film in a local area on the resist film and draining the solution, the first liquid film having a flow and being formed between the resist film and a projection optical system, transferring the pattern of the reticle to the resist film through the first liquid film to form a latent image, supplying a second chemical solution onto the resist film to clean the resist film, heating the resist film, and developing the resist film to form a resist pattern from the resist film.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 11/084,001,filed Mar. 21, 2005 now U.S. Pat. No. 7,524,618, and claims the benefitof priority from prior Japanese Patent Application No. 2004-087420,filed Mar. 24, 2004, the entire contents of both which are incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a resist pattern forming method, asemiconductor apparatus using said method, and an exposure apparatusthereof, and more particularly to a method for forming a resist patternby exposing a resist film formed on a substrate through a liquid inorder to form a latent image and then performing selective development,and a semiconductor apparatus using the method, and an exposureapparatus thereof.

2. Description of the Related Art

An immersion exposure apparatus employs a technique which performsexposure by filling a liquid between a resist film surface and a lens ofan exposure apparatus when a resist film formed on a substrate inprocess is exposed. As apparatuses used in such an exposure method,there is an apparatus disclosed in, e.g., Jpn. Pat. Appln. KOKAIPublication No. 10-303114. This patent reference discloses an apparatus,which has a stage capable of supplying water, immerses an entiresubstrate in water and performs exposure while relatively moving thestage with respect to the exposure apparatus. In the apparatus havingsuch a conformation, since a liquid is supplied to the entire stage,there is a problem that liquid spills from the stage when the stagemoves at a high speed, making a high-speed driving hard.

As a countermeasure for a disturbance of a liquid flow due to movementof the stage, a technique which drives the stage while locally supplyingliquid to a part being exposed is disclosed in “Immersion lithography;its potential performance and issues,” Proc. of SPIE Vol. 5040, pp.724-733, by Soichi Owa and Hiroyuki Nagasaka. The stage can be moved ata high speed by the technique disclosed in the reference. When such atechnique of locally supplying liquid is used, there are problems thatwater remains in an exposure area or the like in a part from which alens is gone, and if performing post-exposure heating to the resist filmin such a state, then a water mark and/or a resist pattern defect due toinsufficient temperature are generated at the part where the water hasremained, for example.

Further, when performing exposure near an edge of a substrate, water mayflow to an edge portion of a resist film in some cases. In such a case,a turbulent in water flow is generated at step between the substrate andthe edge of the resist film, and an air bubble can be caught. When theair bubble reaches an exposure slit area, an exposure trouble maypossibly occur in some cases. There is a problem that a resist patterndefect is generated due to the exposure trouble.

Therefore, in the immersion exposure which performs exposure through theliquid film formed in a local area on the substrate, there is need for aresist pattern forming method which can suppress an occurrence of adefect in a resist pattern.

BRIEF SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided aresist pattern forming method comprising: forming a resist film on asubstrate; mounting the substrate formed the resist film thereon and areticle formed a pattern thereon onto an exposure apparatus comprising aprojection optical system; supplying a first chemical solution onto theresist film to selectively form a first liquid film in a local area onthe resist film and draining the first chemical solution supplied,wherein the first liquid film has a flow, and wherein the first liquidfilm is being formed between the resist film and the projection opticalsystem; transferring the pattern formed on the reticle to the resistfilm, with the first liquid film being formed, to form a latent image inthe resist film; supplying a second chemical solution onto the resistfilm to form a second liquid film on a substantially entire surface ofthe substrate; removing the second liquid film; heating the resist filmformed the latent image therein after the removal; and developing theresist film to form a resist pattern from the resist film heated.

According to another aspect of the present invention, there is provideda resist pattern forming method comprising: forming a resist film on asubstrate; mounting the substrate formed the resist film thereon and areticle formed a pattern thereon onto an exposure apparatus comprising aprojection optical system; supplying a first chemical solution onto theresist film to selectively form a first liquid film in a local area onthe resist film and draining the first chemical solution supplied,wherein the first liquid film has a flow, and wherein the first liquidfilm is being formed between the resist film and the projection opticalsystem; transferring the pattern formed on the reticle to the resistfilm, with the first liquid film being formed, to form a latent image inthe resist film; spraying a gas from a gas injection portion to a partof a surface of the resist film; scanning the gas injection portion overthe substantially entire surface of the substrate to spray the gas onthe surface of the resist film; heating the resist film formed thelatent image therein after the scanning; and developing the resist filmto form a resist pattern from the resist film heated.

According to still another aspect of the present invention, there isprovided a resist pattern forming method comprising: forming a resistfilm on a substrate; mounting the substrate formed the resist filmthereon and a reticle formed a pattern thereon onto an exposureapparatus comprising a projection optical system; supplying a firstchemical solution onto the resist film to selectively form a firstliquid film in a local area on the resist film and draining the firstchemical solution supplied, wherein the first liquid film has a flow,and wherein the first liquid film is formed between the resist film andthe projection optical system; controlling a direction of the flow ofthe first liquid film to flow from an area to which the pattern istransferred towards an edge of the resist film on the substrate when theedge of the resist film is included in the area where the first liquidfilm is selectively formed; transferring the pattern formed on thereticle to the resist film, with the first liquid film being formed, toform a latent image in the resist film; heating the resist film formedthe latent image therein after the removal; and developing the resistfilm to form a resist pattern from the resist film heated.

According to yet another aspect of the present invention, there isprovided a method for manufacturing a semiconductor apparatus,comprising: preparing a semiconductor wafer; forming a resist film onthe semiconductor wafer; mounting the semiconductor wafer formed theresist film thereon and a reticle formed a pattern thereon onto anexposure apparatus comprising a projection optical system; supplying afirst chemical solution onto the resist film to selectively form a firstliquid film in a local area on the resist film and draining the firstchemical solution supplied, wherein the first liquid film has a flow,and wherein the first liquid film is formed between the resist film andthe projection optical system; transferring the pattern formed on thereticle to the resist film, with the first liquid film being formed, toform a latent image in the resist film; supplying a second chemicalsolution onto the resist film to form a second liquid film on asubstantially entire surface of the semiconductor wafer; removing thesecond liquid film; heating the resist film formed the latent imagetherein after the removing; and forming a resist pattern on thesemiconductor wafer by developing the resist film heated.

According to a further aspect of the present invention, there isprovided an exposure apparatus comprising: an exposure unit comprising aprojection optical system which forms a latent image in a resist filmformed on a substrate by transferring a reticle pattern, wherein theexposure unit comprises a first chemical solution supply/drain subunitto selectively form a first liquid film having a flow between the resistfilm in a local area thereof and the projection optical system; and awater processing unit to form a second liquid film on a substantiallyentire surface of the substrate including the resist film formed thelatent image therein, and remove the second liquid film.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a block diagram illustrating a resist pattern forming systemincluding an exposure apparatus according to an embodiment of thepresent invention;

FIG. 2 is a process flowchart illustrating a semiconductor devicemanufacturing process according to an embodiment of the presentinvention;

FIGS. 3A and 3B are views illustrating a state in which cleaning processaccording to an embodiment of the present invention is carried out;

FIGS. 4A and 4B are views illustrating a state in which cleaning processaccording to an embodiment of the present invention is carried out;

FIGS. 5A and 5B are views illustrating a state in which cleaning liquidremoving process according to an embodiment of the present invention iscarried out;

FIG. 6 is a view illustrating a general structure of an exposureapparatus according to an embodiment of the present invention;

FIG. 7 is a plan view showing an example of the arrangement of exposurefields on a substrate;

FIGS. 8A to 8C are views illustrating scanning exposure according to anembodiment of the present invention;

FIGS. 9A to 9C are views illustrating scanning exposure according toanother embodiment of the present invention;

FIG. 10 is a plan view illustrating an order of an exposure of exposurefields when a scanning exposure is sequentially performed according toan embodiment of the present invention;

FIG. 11 is a plan view illustrating an example of droplets remaining ona substrate after the scanning exposure according to an embodiment ofthe present invention;

FIG. 12 is a plan view illustrating a scan direction of an exposure slitarea and a water flow direction when there is a resist film edge in animmersion area;

FIG. 13 is a plan view illustrating a scan direction of an exposure slitarea and a water flow direction when there is a resist film edge in animmersion area;

FIG. 14 is a plan view illustrating a scan direction of an exposure slitarea and a water flow direction when there is a resist film edge in animmersion area;

FIG. 15 is a plan view illustrating a scan direction of an exposure slitarea and a water flow direction when there is a resist film edge in animmersion area; and

FIG. 16 is a plan view illustrating a scan direction of an exposure slitarea and a water flow direction when there is a resist film edge in animmersion area.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments according to the present invention will now be describedhereinafter with reference to the accompanying drawings.

A resist pattern forming apparatus 100 according to an embodiment of thepresent invention comprises a resist film forming unit 110, an exposureunit 120, a water processing unit 130, and a developing unit 140. Theresist film forming unit 110 forms a resist film on a substrate.Furthermore, it can be provided with a function which cleans a surfaceof the resist film formed. The exposure unit 120 comprises an immersionexposure device which selectively forms a liquid film in a local area onthe resist film and exposes the resist film through the liquid filmformed, and forms a latent image in the resist film. The exposure unit120 further comprises a chemical solution supply/drain subunit 125 forforming the liquid film. The water processing unit 130 cleans the resistfilm having the latent image formed therein, and the developing unit 140elicits the latent image in the resist film by development, therebygenerating a resist pattern.

A resist pattern forming method according to an embodiment of thepresent invention will now be described hereinafter based on a processflowchart shown in FIG. 2, with reference to FIGS. 3 to 11.

After an antireflection film application material is dropped, spun andspread over a semiconductor substrate, a heat treatment is performed sothat an antireflection film having a thickness of approximately 50 nm isformed (step ST201). An ArF chemically amplified type resist filmcontaining an acid-forming agent is formed with a film thickness of 200nm on the antireflection film (step ST202). The chemically amplifiedtype resist can be formed in accordance with the following procedure. Achemically amplified type resist application material is spread over theantireflection film by spin coat method. Then, heat treatment isperformed, thereby removing a solvent contained in the resistapplication material.

According to a surface analysis of the ArF chemically amplified typeresist film performed additionally, it is found that an acid-formingagent or an acid-trapping agent (e.g., amine) is existed on a filmsurface. In order to remove the acid forming agent or the acid-trappingagent on the resist film surface, deionized water is supplied onto theresist film so that cleaning process is effected (step ST203). Theacid-forming agent and the acid-trapping agent on the resist filmsurface can be removed by the cleaning. It is to be noted that aprotection film can be further formed on the resist film to eliminatethe affect of the acid-forming agent or the acid-trapping agentremaining on the film surface after the heat treatment in some cases.There may be a case where the acid-forming agent or the acid-trappingagent still exists on the protection film depending on the heatingcondition, thereby requiring the same cleaning process.

FIGS. 3A and 3B are views illustrating a state in which cleaning processaccording to an embodiment of the present invention is carried out. FIG.3A is a plan view showing a state in which the cleaning process iscarried out, and FIG. 3B is a side view showing a state in which thecleaning process is effected.

As shown in FIGS. 3A and 3B, the semiconductor substrate 10 is held on asubstrate support portion 11. The substrate support portion 11 is spunby a drive portion 12. Deionized water (a third chemical solution) 14 asa cleaning liquid is supplied to the semiconductor substrate from acleaning nozzle 13 while spinning the semiconductor substrate 10. In thecleaning process, as shown in FIG. 3A, the cleaning nozzle 13 isreciprocated between one end and the other end of the substrate 10. Whenthe cleaning nozzle 13 is positioned at a peripheral portion of thesubstrate 10, a moving speed of the nozzle 13 is made slower than amoving speed of the nozzle 13 positioned at the central portion of thesubstrate 10. As a result, amount of the cleaning liquid supplied perunit area of the substrate 10 becomes substantially identical, therebyenhancing the cleaning effect. It is to be noted that, if the nozzle 13moves in a uniform speed, the same effect can be obtained by changingthe number of revolutions of the substrate in inverse proportion to aposition of the nozzle in the radial direction.

Moreover, the chemical solution is not limited to deionized waterdescribed in the embodiment as long as it is a chemical solution whichcan readily remove these materials. If a time required for cleaning islong, then short-time processing is enabled by using oxygen dissolvedwater, hydrogen dissolved water, carbonic acid dissolved water or thelike. In case of using oxygen dissolved water, cleaning can beeffectively performed by applying a dissolved oxygen of 10 ppm or belowwithout giving damages on the film surface. Additionally, in case ofusing hydrogen water, an application of water substantially saturatedwith hydrogen (approximately 1.2 ppm) is effective. By selecting anappropriate chemical solution based on, e.g., an electronic potentialgenerated on the film surface when the film surface is exposed to thechemical solution, or an electronic potential in the acid-forming agentor in the acid-trapping agent, the chemical solution gives betterperformance when the chemical solution is used under a condition thatthe acid-forming agent or the acid-trapping agent can be readilyreleased from the film surface.

Further, as shown in FIGS. 4A and 4B, the nozzle 13 may be turned backbetween the central portion of the substrate 10 and one end of theperipheral portion of the substrate 10. FIGS. 4A and 4B are viewsshowing a state in which cleaning process according to an embodiment ofthe present invention is performed. FIG. 4A is a plan view showing astate in which the cleaning process is effected, and FIG. 4B is a sideview showing a state in which the cleaning process is carried out. InFIGS. 4A and 4B, like reference numerals denote parts the same as thosein FIGS. 3A and 3B, thereby eliminating the explanation thereof.

Furthermore, although water is supplied in a direction orthogonal to theprimary surface of the substrate 10, the present invention is notlimited thereto. For example, water 14 may be supplied in a samedirection to a spinning direction of the substrate 10. As a result, theimpact shock when the deionized water 14 strikes on the film surface canbe moderated, and cleaning can be carried out without damaging the filmsurface. Moreover, the acid-forming agent or the acid-trapping agentadsorbed to the film surface can be efficiently-removed by supplyingwater 14 in a direction opposite to the spinning direction of thesubstrate 10. Additionally, the acid-forming agent or the acid-trappingagent removed from the film surface can be efficiently discharged to theoutside of the substrate by supplying water 14 toward the outerperiphery of the substrate 10.

Subsequently, resist film surface drying process is carried out (stepST204). As shown in FIGS. 5A and 5B, in the drying process, a gas 22from which acid and alkali are filtered is sprayed on the primarysurface of the substrate 10 from an air knife 21. An area to which theair knife 21 sprays air is only a part of the substrate surface. Inorder to spray air over an entire surface of the substrate 10, the airknife 21 scans the surface of the substrate 10 from one end to the otherend. In this case, the substrate 10 may be spun or may be remainedstationary. FIGS. 5A and 5B are views illustrating a state in whichcleaning liquid removing process is carried out according to anembodiment of the present invention. FIG. 5A is a plan view showing astate in which the cleaning liquid removing process is affected, andFIG. 5B is a side view showing a state in which the cleaning liquidremoving-process is performed. The deionized water 14 may be removedfrom the film surface but be left some extent adsorbed on the filmsurface. It is desirable that a direction of the air 22 sprayed from theair knife 21 is an advancing direction of the air knife 21. By settingthese directions to be the same, water can be efficiently removed in ashort time. A key point of removing the deionized water 14 in theprocess is not to perform by heat treatment or by drying under a reducedpressure. If the heat treatment or drying under the reduced pressure isperformed, the acid-forming agent and the acid-trapping agent seep fromthe inside of the resist film and appear again on the film surface, andhence the effect of the cleaning process performed is lost. In case of asubstrate having a small diameter, the substrate may be spun and driedwithout using the air knife.

After the cleaning process, the substrate is carried to a scanningexposure apparatus (step ST205). A semiconductor device pattern formedon a reticle is transferred to the resist film by using the scanningexposure apparatus, thereby forming a latent image in the resist film(step ST206).

The exposure apparatus used in the embodiment is of an immersion type.FIG. 6 is a view showing a general configuration of the exposureapparatus according to an embodiment of the present invention. A reticlestage 31 is disposed below an illumination optical system (not shown).The reticle 32 is provided on the reticle stage 31. The reticle stage 31can move horizontally. A projection lens system 33 is disposed below thereticle stage 31. A wafer stage 34 is disposed below the projection lenssystem 33. The semiconductor substrate 10 subjected to theabove-described processing is set on the wafer stage 34. The wafer stage34 moves horizontally together with the semiconductor substrate 10. Asupport plate 37 is provided around the semiconductor substrate 10.

A fence 35 is disposed under the projection lens system 33. Pair ofwater supplier/drainer 36, which performs supply of water (a firstchemical solution) into the fence 35 and drain off water inside thefence 35, is provided on sides of the projection lens system 33. Whenexposure is performed, a space in an area surrounded by the fence 35 andbetween the projection lens system 33 and the substrate 10 is filledwith the liquid film of water (a first liquid film). An exposure lightemitted from the projection lens system 33 passes through a layer ofwater and reaches an area being irradiated on the resist film. An imageof a mask pattern (not shown) of the reticle 32 is projected onto theresist film on the substrate surface in that irradiation area, therebyforming a latent image therein.

FIG. 7 is a plan view showing an example of the arrangement of exposurefields being formed on the substrate. The mask pattern formed on thereticle is projected and transferred to each rectangular exposure field41 on the substrate 10 by a scanning exposure. FIGS. 8A to 8C and FIGS.9A to 9C are views illustrating the scanning exposure according to anembodiment of the present invention. In the scanning exposure, forexample, as shown in FIGS. 8A to 8C, an exposure slit area 51 scans theexposure field 41 from an upper side to a lower side of a page surface.Alternatively, as shown in FIGS. 9A to 9C, the exposure slit area 51scans the exposure field 41 from the upper side to the lower side of thepage surface.

FIG. 10 is a plan view showing an example of an exposure order of theexposure fields when the scanning exposure is sequentially performed.Each of an upward arrow and a downward arrow in FIG. 10 indicates adirection along which the exposure slit area moves. As shown in FIG. 10,when one exposure field is subjected to the scanning exposure and thenanother scanning exposure is performed to an adjacent exposure field,directions of the scanning are opposite each other. The entire surfaceof the substrate is exposed by repeating such operations.

During the scanning exposure, the water supplier/drainer 36 drains waterto prevent water from remaining outside of the surrounded area by thefence 35. However, droplets of residual water 71 are produced on thesubstrate 10 as shown in FIG. 11, if the resist film on the substrate ishydrophobic (a contact angle of the resist film to water is large), amoving speed of the stage is high, an acceleration and decelerationspeed of the stage is high, or an exposure area is relatively large.When the next heat treatment (post exposure bake) is performed withwater locally remained on the resist film as described above, heat isabsorbed by the water remained and amount of heat supplied to the resistfilm is reduced as compared with other part, a reaction in the resistfilm caused by heating is insufficient at that part, resulting to causea defect in a line width. If the resist is a positive resist, anunopened defect is generated. If the resist is a negative resist, anopen defect is disadvantageously generated.

In order to prevent these problems, it is desired to remove the residualwater 71 remained on the substrate after the immersion exposure. Ingeneral, a spin dry is used to remove the residual water on thesubstrate 10. However, since the residual water 71 is scattered on thesubstrate 10, it is hard to remove the residual water 71 completely bythe spin dry.

In the present embodiment, the following processing is carried out toremove the residual water 71. Specifically, the substrate having theresist film with the latent image formed therein is carried to the waterprocessing unit 130 (step ST207). Deionized water (a second chemicalsolution) is supplied onto the entire surface of the substrate 10,thereby forming a liquid film (a second liquid film) on thesubstantially entire surface of the substrate 10 (step ST208). Like thedrying after the cleaning process in step ST204, the liquid film of thedeionized water is removed by the spin dry or the air knife (stepST209). The water on the film surface (the residual water+the liquidfilm) is completely removed by the processing. However, if the watercannot be completely removed, it may be preferred to form a state inwhich the water is equivalently adsorbed among chips. By adsorbing thewater among chips in such a manner, a desired resist pattern can finallybe obtained by feeding back a dimensional shift produced after postexposure bake to a mask dimension used in exposure in advance as adimension conversion difference. It is to be noted that water is used inthe example, but the present invention is not limited thereto. It canalso be used a chemical solution which has a good affinity to water,does not damage the resist film, and has a heat of evaporation smallerthan that of a droplet (in this embodiment, water: evaporation heat=583cal/g at 100° C.), e.g., an alcohol-based or ether-based chemicalsolution, or dissolve such a chemical solution in a solvent having thesame component as the droplet (same component as the first chemicalsolution). It is much better that a chemical solution to be used hasquick-drying properties. Such processing is also effective to not onlythe resist film surface but also the protection film surface when theprotection film is used.

Further, in the immersion exposure, the resist pattern may not be formedin a predetermined accuracy because a photosensitive agent or the likeseeps into the water from the resist film and the photosensitive agentadsorbs again to the resist surface at a stagnant part, for example. Inthe present embodiment, the photosensitive agent or the like which hasadsorbed again to the resist film surface can be cleaned out bysupplying/removing the water after the immersion exposure. As a result,the accuracy of the resist pattern can be improved. It is to be notedthat a chemical solution having a heat of vaporization smaller than thatof water, e.g., an alcohols or ethers, can be supplied/dried on theresist film surface to remove the water adsorbed on the surface aftersupplying/draining the water, thus more homogeneous baking can becarried out in the next baking process. Such processing is effective tonot only the resist film surface but also the protection film surfacewhen it is used.

The substrate subjected to the above-described processing is carried toa baker where the substrate is heated (PEB: post exposure bake) (stepST210). Diffusion and an amplification reaction of an acid generated inthe exposure step are executed during the heating. Then, the substrateis carried to the developing unit 140 where development is performed,thereby forming an ArF resist pattern (step ST211).

Meanwhile, the process from at least the exposure unit to the baker unitthrough the water processing unit after exposure should be performed ina controlled atmosphere. It has been revealed that a concentration of abasic material in the atmosphere must be controlled to 10 ppb or less tosuppress deactivation of the acid generated in the resist to an extentthat formation of a resist pattern is not affected. Moreover, anexperimental result says that it is desirable to manage a processingtime, including a carriage time, within a range of ±10%.

According to the embodiment, the residual water on the resist filmsurface can be removed by supplying water onto the resist film after theimmersion exposure and removing the water. As a result, occurrence of apattern defect can be suppressed.

It is to be noted that supply of the deionized water (step ST208) andremoval of the deionized water (step ST209) are carried out to removethe residual water 71 scattered on the substrate after affecting theimmersion exposure. However, it is also effective to scan the air knife21, which sprays a gas from a slit-like nozzle to the substrate locally,on the surface of the substrate to remove the residual water 71 like thedrying process at step ST203. Alternatively, an air gun may be scannedon the surface of the substrate in place of the air knife. However, theair knife has a higher residual water removing capability than the airgun. Therefore, it is preferred to remove the residual water 71 by usingthe air knife rather than the air gun.

A description will now be given as to a case of performing exposure inthe peripheral portion of the substrate in the scanning exposure. FIG.12 shows an example where water is caused to flow in a water flowdirection 72 a while scanning the exposure slit area 51 in a scandirection 54 in the exposure area 41. In FIG. 12, reference numeral 38denotes an immersion area surrounded by the fence 35. The figureillustrates that air bubbles 73 taken in at a step of the resist filmedge 70 are moved by the water flow and reach the exposure slit area 51,thereby causing an exposure defect. It is to be noted that air bubblesare also generated when the immersion area is at a boundary between thesubstrate 10 and a support plate (not shown).

In order to solve the problem, it is desired to control a direction ofthe water flow with respect to the edge of the resist film. As shown inFIG. 13, when a resist film edge 70 exists in the immersion area 38, itis desired to control a water flow direction 72 b in a direction fromthe exposure slit area 51 toward the edge 70. Air bubbles 73 generatedat the edge 70 can be effectively discharged without reaching theexposure slit area 51 by forming the water flow in this manner. It ismore preferable to scan the exposure slit area 51 in the water flowdirection at this moment since a rise in temperature of the flowingwater can be prevented. In other words, the substrate 10 is moved in adirection opposite to the water flow direction.

Further, when a wafer edge exposure is performed, if a substrate edgeexists in a direction substantially parallel with a scan direction ofthe exposure area in the immersion area, it is desired to provide awater pressure difference in the immersion area. FIG. 14 shows anexample where water is caused to flow in a water flow direction 72 cwhile scanning the exposure slit area 51 in the scan direction 54.

In the process shown in FIG. 14, air bubbles are taken in at an edge 70,a conductance of the water at that portion becomes small, thus apressure balance is lost. As a result, air bubbles flow to the innerside of the substrate. In order to prevent the phenomenon, it is desiredto control a water flow direction 72 d in a direction from the innerside of the substrate toward the outer side thereof as shown in FIG. 15.Specifically, it is desired to set a pressure of the water supply to behigher on the inner side of the substrate or set a drain pressure to behigher on the substrate edge side. Air bubbles can be discharged to theoutside of the substrate by setting the water flow direction 72 d towardthe outer side of the substrate by using such techniques. Furthermore,as shown in FIG. 16, a water flow direction 72 e may be caused to directfrom the inner side toward the outer side of the substrate andorthogonal to an exposure area scan direction 54.

It is to be noted that, in the present embodiment, the degasifieddeionized water is used as the water interposed between the lens and thesubstrate in the exposure process, but the present invention is notlimited thereto. It can also be used a liquid in which an alkaline ionof, e.g., group I or group II element, is added to increase a refractiveindex or in which an acid ion is added to reduce an absorptioncoefficient. In case of using an exposure apparatus which has a smallabsorption coefficient with respect to an exposure light and is matchedwith a specific refractive index, it can be used any liquid having aspecific refractive index as long as it does not damage the lens systemor the like.

Although the present invention relates to an exposure using an ArF (193nm) light, it can be applied to an exposure using a KrF (248 nm) lightby performing the same processing with similar accuracy. Moreover, ithas been confirmed that patterning can be accurately carried out byusing a fluorine-based oil as a first solvent in an F₂ (157 nm)exposure.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventionconcept as defined by the appended claims and their equivalents.

1. An exposure apparatus comprising: an exposure unit comprising aprojection optical system which forms a latent image in a resist filmformed on a substrate by transferring a reticle pattern, wherein theexposure unit comprises a first chemical solution supply/drain subunitto selectively form a first liquid film having a flow between the resistfilm in a local area thereof and the projection optical system; and awater processing unit to form a second liquid film on a substantiallyentire surface of the substrate including the resist film formed thelatent image therein, and remove the second liquid film, wherein thewater processing unit comprises a cleaning nozzle supplying a secondchemical solution onto the resist film formed on the substrate to formthe second liquid film, and wherein the cleaning nozzle scans oversubstantially an entire surface of the substrate at a moving speed so asto control an amount of the second chemical solution supplied per unitarea of the substrate to be substantially identical.
 2. The exposureapparatus according to claim 1, wherein the first chemical solutionsupply/drain subunit controls a direction of the flow of the firstliquid film to be a direction from an area to which the pattern istransferred toward an edge of the resist film on the substrate when theedge of the resist film is included in the area where the first liquidfilm is selectively formed.
 3. The exposure apparatus according to claim2, wherein the direction of the flow of the first liquid film iscontrolled by a pressure difference of the first chemical solutionforming the first liquid film within the area where the first liquidfilm is selectively formed.
 4. The exposure apparatus according to claim1, wherein the water processing unit comprises a gas injection portionspraying a gas to a part of the surface of the resist film to remove thesecond liquid film therefrom.
 5. The exposure apparatus according toclaim 4, wherein the gas injection portion scans over substantiallyentire surface of the substrate.
 6. The exposure apparatus according toclaim 4, wherein the gas injection portion is an air knife.
 7. Theexposure apparatus according to claim 1, wherein the first chemicalsolution supply/drain subunit comprises a fence partitioning the areawhere the first liquid film is selectively formed, and a chemicalsolution supplier/drainer supplying the first chemical solution toinside the fence and draining off the first chemical solution frominside the fence.
 8. The exposure apparatus according to claim 1,wherein the moving speed of the cleaning nozzle is controlled as afunction of distance from the center of the substrate rotating at aconstant rate to supply a substantially identical amount of the secondchemical solution per unit area of the substrate.
 9. The exposureapparatus according to claim 1, further comprising a resist film formingunit forming the resist film on the substrate, wherein one of materialsconstituting the resist film is an acid-forming agent or anacid-trapping agent, the resist film forming unit supplying a thirdchemical solution to remove the acid-forming agent or the acid-trappingagent on the surface of the resist film before transferring the resistpattern.
 10. The exposure apparatus according to claim 9, wherein thethird chemical solution dissolves the acid-forming agent or theacid-trapping agent.
 11. The exposure apparatus according to claim 10,wherein the third chemical solution is one of deionized water, ozonedissolved water, hydrogen dissolved water, or carbonate dissolved water.12. The exposure apparatus according to claim 1, wherein the exposureunit comprises a wafer stage to mount and move the substrate, a movingdirection of the wafer stage is substantially opposite to the directionof the flow of the first liquid film.